Electrical heating unit.



E. G. VAN WiE & R. W. DAVENPQRT. ELECTRICAL HEATING UNIT! APPLICATION men NOV. 25, 1912.

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UNITED STATES PATENT OFFICE.

EDWIN G. VAN

AND RANSOM W. DAVENPORT, OF DETROIT, MICHIGAN, ASSTGN'ORS TO DETROIT STOVE WORKS, OF DETROIT, MICHIGAN, A CORPORATION OF MICHIGAN.

nLncrnIonL HEATING unrr.

Specification of Letters Batent.

Patented Jane 15, 1915.

Application filed November 25, 1912. Serial No. 733,512.

useful Improvements in Electrical Heating Units, of which the following is a specification, reference being had therein to the accompanying drawings.

The invention relates to electrical heating units, and particularlyto that type in which in the same general the heat-developing resistor is wound spirally upon a supporting core of insulating material. I

It" is one of the objects of the invention to obtain a construction which will be more eflicient in heating where the object to be heated is arranged. on one side only of the unit.

It is a further object to facilitate the at tachment and detachment of the units so that theymay be removed or replaced when necessary.

A furtherobject is to rigidly support the resistor Without conducting any heat there- 'fating socket contact members in the stationary part, which will automatically complete from at points of support, thereby facilitating the quick heating of said resistor.

In the drawings: Figure l is a perspective view of the unit. Fig. 2 is a cross section through an oven, showing the arrangement of the'heating units therein. Fig. 3 isa cross section through one of the units.

.It is usual with heating units of the type to which my invention belongs to employ a core of round section for supporting the spiral resistor. This interposes the core between one-half of the surface of the resistor and the work which is to be heated, and thereby reduces the heating etlicieney.

Vith my improved construction, in place of a core of round cross section, I employ a triangular shaped core, so that the direct radiation from two-thirds of the conductor is direction, while only one-third is shielded by the core.

As shown in detail, A is a core member formed of insulating material or of metal having an. insulating facing. This core member is preferably of a (shaped cross section forming projecting ridges B spaced from each other at substantially equal angles.

is the resistor in the form of a wire or ribbon, and which is spirally wound upon the core A, being in contact with the several ribs and assuming a triangular shape. D is a head at one end 0 the core member A, upon which 1s mounted the terminal con tacts E and E secured to suitable insulator supports and connected with the ends of the resistor.

I In use, the units are arranged as shown in Fig. 2, with one of the sides of the triangle parallel .with theoven wall or heat-reflecting surface F, while the other two sides of the triangle are in opposite oblique positions.

.This willpermit directradiation of heat from the resistor on the two sides G and G without any shielding from the core, while the third side G which is behind the core, will radiate heat against the reflecting surface F, which will distribute it downward. Thus two-thirds of the direct radiation from the resistor is available and passes into the work, while the radiation from the third side is reflected back to increase the effect.

When the unit is inserted in an oven or other position whereit is to be used, the terminal contacts E and IE will engage cooperthe electric circuit.

What we claim as our invention is:

1. An electrically heating. unit comprising a supporting frame formed with an opening and a boss surrounding the opening which projects beyond the frame, It member received within said boss said member being formed with radially extending longi tudinally disposed ribs, and a coil constituting a resistor wound about the member and contacting with the edges of the ribs, the contact of the resistor with the ribs bending the wire of which the resistor is formed to produce triangular windings.

2. The combination with a casing having a top bottom and sides of an electrical heating element insertible within the casing immediately beneath the top of the same. said element having radially extending longitudinally disposed ribs, one of said ribs being of greater width than the remaining ribs, a coil constituting a resistor wound about the member and contacting with the edges of the ribs, the member being so supported that in end elevation the longer rib is disposed short horimntal heating surface and cam In testimon whereof We afiix our signa- 1 L: w I Q I .J

verglng ouhquely dISPOSGQ heam-ng'surmces bums m presence ortwa wltnesses.

01" greater length than said hOllZOlfiltBl heat- 7 in surfaces whereby heat] Will Q Q E fi lirecdy from the resistor on two sifiies and whom shielvfing. from the memb r, the heat Wimesses; mdiwing the 'third @416 being reflect-361 Annmmm I. ADAMS,

dmvn'wai'dlly by the "50p of JAMES P, BARRY. 

